Research Projects

Mangroves found in most tropical and subtropical marine regions in the intertidal zonesof river deltas hold a greater diversity of flora, fauna, and microorganisms. Being associated withthe marine ecosystem, they deal with the dynamic temperature, tidal regime, pH, salinity andheavy metals. Among the microorganisms present in these environments, bacteria respondquickly to this dynamic conditions at both phenotypic and genotypic levels. The bacterialcommunity forms the biofilm in such fluctuating environmental conditions for its growth andsurvivability. The biofilm formation ability of bacteria helps them to adhere to every substrateand operate various nutrient cycling processes. However, fluctuating environmental parametersaffect their efficiency in operating various biogeochemical cycles. The current research focuses100on the effect of various stressors on the mangrove bacteria and thereby understanding their rolein the regulation of ecosystem-level processes. In this study, a comparative analysis was donebetween Bacillus stercoris GST-03 (a gram-positive bacterium) and Pseudomonas balericaDST-02 (a gram-negative bacterium). B. stercoris GST-03 was found to be stress toleratingbacterium showing tolerance towards lower pH. In contrast, P. balerica DST-02 was found to bea good biofilm former. B. stercoris GST-03 shows cellulose degradation potential, whichindicates it will play a crucial role in cellulose degradation in the mangrove ecosystem. Inaddition, B. stercoris GST-03 shows higher tolerance to temperature, salinity, heavy metals andUV compared to P. balerica DST-02. The identification of pslB and tasA in P. balerica DST-02and B. stercoris GST-03, respectively, validates their biofilm-forming ability. The presence ofgenes, celA and celB validates the cellulose degradation ability of B. stercoris GST-03. Thefluctuation in the environmental parameters leads to the production of ROS in both strains. ROSproduction was found to be minimum during the optimum growth conditions. Further, theoxidative stress-mediated DNA damage and repair mechanism were studied. The production ofDNA damage products and antioxidants co-occurs. The condition at which the correlationbetween them imbalances leads to irreparable DNA damage in bacteria. The resulting output ofthe expression analysis of genes involved in the NER and SOS response pathway depicted theDNA damage at pH 9, and Pb concentration 1000 might be irreparable in B. stercoris GST-03. Incontrast, DNA damage at pH 4 and 9, 1000 ppm of Pb and 200 ppm of Cd might be irreparablein P. balerica DST-02. The microcosm study revealed that B. stercoris GST-03 shows moretolerance and produces dense biofilm in the stress condition predicted for the year 2100compared to P. balerica DST-02. The present work demonstrates the effect of various stressorson the mangrove bacteria that will help to understand the fate of the mangrove bacteria in futureclimate change scenarios.